List of amino acids

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Amino acids are molecules that consist of atoms forming two specific functional groups (amines and carboxylic acids). There are potentially thousands of amino acids, but the most important (at least to humans) are the twenty of them that are coded for by our DNA and make up the proteins in our bodies.

The 20 amino acids coded for in human DNA[edit]

Amino Acid Nucleotide Sequence(s) Essential?a Chiral?b
Alanine GCU, GCC, GCA, GCG No Yes
Arginine CGU, CGC, CGA, CGG, AGA, AGG No if you're an adult Yes
Asparagine AAU, AAC No Yes
Aspartic acid GAU, GAC No Yes
Cysteine UGU, UGC Sort of[note 1] Yes
Glutamine CAA, CAG No Yes
Glutamic acid GAA, GAG No Yes
Glycine GGU, GGC, GGA, GGG No No
Histidine CAU, CAC Yes Yes
Isoleucine AUU, AUC, AUA Yes Yes
Leucine UUA, UUG, CUU, CUC, CUA, CUG Yes Yes
Lysine AAA, AAG Yes Yes
Methionine AUG Yes Yes
Phenylalanine UUC, UUU Yes Yes
Proline CCU, CCC, CCA, CCG No Yes
Serine UCU, UCC, UCA, UCG, AGC, AGU No Yes
Threonine ACU, ACC, ACA, ACG Yes Yes
Tryptophan UGG Yes Yes
Tyrosine UAC, UAU No Yes
Valine GUU, GUC, GUA, GUG Yes Yes

a Essential in this context means that the amino acids must be consumed as part of the human diet, they cannot be made (in humans) by converting one amino acid into another.

b Posh word for "looks like a pair of gloves" (chiral molecules are like gloves in that they are made from all the same parts, but are mirror images of each other)

2 special amino acids[edit]

Amino Acid Nucleotide Sequence Essential? Chiral?
Selenocysteine UGA No[note 2] Yes
Pyrrolysine UAG[note 3] N/A Yes

Works cited[edit]


  1. Cysteine can be essential in rare cases, but is usually not.
  2. Selenocysteine is produced in humans. Normally, UGA means "stop", but through a complicated process, it will code for selenocysteine.
  3. No, this isn't a mistake. Pyrrolysine is used in bacteria, not humans, where it is coded for using UAG.